Samsung MD65C User Manual page 244

Other issue
In power-saving mode, when the input source is DisplayPort,
PC display settings cannot be saved.
When booting the PC with the input source set to
DisplayPort, the BIOS and booting screens do not appear.
→
Go to System General and set Max. Power Saving
output settings again. Ensure the set is turned on.
Boot the PC when the set is turned on or when the input source is not DisplayPort.
to Off. Alternatively, configure the PC display
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